A eukaryote is any cell or organism that possesses a clearly defined nucleus. Eukaryotic cells form the foundation of complex, multicellular life, including apple trees, mushrooms, fish and humans.

While prokaryotic cells do not have membrane-bound structures, they do have distinct cellular regions (Figure 1). In prokaryotic cells, DNA bundles together in a region called the nucleoid. Primitive ...

More than 1.5 billion years ago, a momentous thing happened: Two small, primitive cells became one. Perhaps more than any event—barring the origin of life itself—this merger radically changed the ...